1. Field of the Invention
This invention relates generally to mechanical wire strippers and more particularly to automatic mechanical wire strippers which are self-contained and portable.
2. Description of the Prior Art
Wire strippers are devices used to strip a portion of insulation from one end of a conductive wire, thereby leaving an exposed conductive element ready to be connected as required. A variety of automatic devices have been employed to perform this function.
The mechanical method of wire stripping refers to any method where insulation cutting blades act on the insulation portion of the wire in a mechanical fashion.
Previous devices which employ this mechanical method include hand-held and manual-operated wire strippers, manual-operated bench strippers, automatic bench strippers, automatic rotary strippers, manual-operated rotary strippers.
Automatic strippers are favored because they provide power driven precise stripping, but they generally comprise heavy motors which are generally electrically or pneumatically powered air cylinders requiring cumbersome power cords and/or pneumatic lines which limit portability and movement.
Those devices which offer the convenience of portability, usually do not provide the accuracy or power actuation of automatic wire strippers.
Wire strippers are widely used in many industries including, for example, the aerospace manufacturing industry.
The electrical wire of an airplane generally involves the use of a wiring harness which may contain hundreds of individual wires and may weigh several hundred pounds. The wire harness is necessarily long, heavy, and cumbersome. Generally, on a first end of the harness, all of the wires are stripped and fitted with terminals for connection to respective first terminals in the aircraft. The wires in the first end of the harness are generally stripped with automatic bench mounted wire strippers. A wiring harness is generally assembled from the separate wires on a harness board. The second ends of the wires are stripped, crimped and terminated after the harness is assembled on the harness board. The second end is generally cut and stripped by manual hand held stripped because it is not possible to bring the heavy automatic equipment to where the second end is located in the harness.
Each stripped end of wire must meet certain industry specifications. First, standard die blades should be used so the electrically conductive elements are not damaged. Second, each end should be "semi-stripped" or "stripped".
A wire is fully stripped when a portion of insulation, referred to as a slug, has been completely separated from the rest of the wire leaving an exposed conductive portion equal in length to the removed slug. A wire is "semi-stripped" when the slug is separated from the rest of the insulating material, but not completely removed from the conductive portion of the wire. By remaining on the end of the conductive portion, the slug performs the function of protecting the stripper conductive portion from becoming frayed. As used herein the terms "strip", "stripped" and "stripping" shall means and include both full and semi-stripping unless otherwise indicated.
Precision and accurate repeatability are desired of any stripper. Strip length repeatability is very important. A specific strip length is required for each particular contact type. The strip length must be precise but easily adjustable. To this end, automation is preferred over manual operation. To the extent that any operator controlled action can be replaced by automatically controlled action, repeatability and precision will be improved.
Reliability and convenience are also improved with the use of automation.
A preferred stripper will also allow several functions to be adjustable. For instance, a stripper should be able to receive and strip wires of different gauges. A stripper should further allow for the adjustment of the length of insulation to be stripped and the positioning of the semi-stripped slug.
The ease and rapidity with which the wire stripper performs its function is also of utmost importance.
In the aerospace industry, the first end of the harness is stripped and terminals applied on a work bench. These wires are usually mechanically stripped on a bench with a large automatic fixed-in-place wire stripper having at least most of the aforementioned features including, precision, accurate repeatability, reliability, convenience, adjustability, compliance with industry standards and specifications, and preferably automatic.
The second end of the harness contains wires that are preferably not stripped until after they are cut to the required length on the harness board. These wires are best stripped at the location where the second end is to be fitted with a terminal and connected to a mating terminal on a device or bus. This requires the use of a wire stripper which allows an operator to maneuver in a variety of positions and different locations. A heavy stationary mounted stripper cannot be used. Manually operated strippers are not accurate and are fatiguing and potentially injurious to use. A wire stripper which is most suitable for working on the second end of a harness should be, inter alia, small, automatic, lightweight, portable, and should not require the use of lengthy and cumbersome power cords or air lines.